If you run a hypervisor on your system putting a different mouse cursor for both the host and the guest can let you tell them apart. If you want to install many more colors you can search the repositories for cursor or if you just want many different colors install the oxygen-cursor-theme-extra package. To have a a different style for applications to install you can install the qt-style-plugin-plastique package.

If you select text on X11 you can do what is middle click paste the selected text with the middle mouse button by clicking down on the scroll wheel.

To find out what version of softare you have you can view the ubuntu packages website from whatever kind of computer you are on. On the command line you can run